Old Mustard Yuuummy Capacitors Discussion

[sarakisof]

Hello folks,  from my childhood i was that child who loved mustard and hated ketchup sause for some reason i cannot explain 

For the sake of my previous repair projects on old vintage tube amps & radios, combo organs and so, realised that there are many of those tasty Mustard (mostly Mullard) caps that maybe in the future need to be replaced. It is not that they are not functional, but it will not hurt to get some changed just for prevention purposes. Some of them have cracks, you know  8)
As i was messing around with google about them just for fun, realised they are a bit hard to find, ebay could be an option, but they are too pricey wherever i looked in.
So i think it would be a good idea to discuss here about options, alternatives, suppliers for getting them in fair bulk prices.
If it is wise to use other type in replacing them, or its critical to be the same (i guess it does), what brands (Mullard is the only way?), NOS options, maybe by scrapping old things/ spare parts etc. whatever you have to shar , feel free to express yourself ...
Any clever, crazy idea  welcome 

 

[Rob Flinn]

Unless mustard caps are smashed to bits they don't normally need replacing.    I even have one that looks a bit squashed that work fine.

 

[Khron]

Film caps.

 

[sarakisof]

Unless mustard caps are smashed to bits they don't normally need replacing.    I even have one that looks a bit squashed that work fine.

yeap thats why i said its needless in most cases but just for the record and the flow of discussion...

Film caps.

so no affect on signal tone, freq etc. i guess, mustard same type is not critical huh? (speaking of same value obviously)

Flea markets for unfunctional/ garbage old amps etc. spare parts would be a good idea i suppose, if i am about to replace with same exact thing.

 

[Khron]

Any particular reason for that?

if i am about to replace with same exact thing.

 

[sarakisof]

Just rumors  ;D 

 

[rackmonkey]

I don’t buy the magic with those things. The majority of those ancient mustard caps and similar are simply metallized polyester dielectric (usually mylar), which does introduce more distortion than polystyrene or polypropylene and can thus have something of a “sound” (see Cyril Bateman’s analysis which can be downloaded from multiple places). If you want to replicate that, pick a modern metallized polyester (specifically mylar) dielectric cap. I challenge you to hear a difference.

 

[Squeaky]

Perhaps nit-picking but I think that the old mustard caps are film-foil not metallized polyester. Materials are the same but construction (and thicknesses) are different. What I use in most of the guitar amps I build are the Cornell Dubilier WMF series caps. These are also film foil polyester caps and probably a reasonable modern substitute.

 

[rackmonkey]

You’re right. They are film/foil as I cracked one open ages ago and looked inside. Luckily I still had that cap and I went back and checked and sure enough they are separate layers.

So my comment stands with the caveat that you find a modern film/foil polyester to replace with. The CDE WMF suggestion then is spot on.

 

[Tubetec]

I was lucky enough to get a few trays of these years ago , in a lot along with a homemade oscilloscope ,
I never realised what they were asking on ebay , 10 euro's a piece by the looks and rising ,
The axial mounted component is getting harder to find I normally end up using box caps with radial pins ,
For point to point tube stuff , axial is usually  better , Marshall amps best era stuff used the Mustard ,so did Hiwatt,WEM ,Neve used them in the good old days too .

 

[AusTex64]

https://www.sozocapacitors.com/sozo-nexgen-mustard-vintage-capacitors/

 

[fazer]

I have an old marshall 50 model 1987.  Its all mustard caps.  The only problem I had with them in 50 years of ownership is the .002 off the V1 1st stage.  It got microphonic.  The weird thing is I replaced it and thought the sound had less life in it.  The microphonic nature created a resonance in a good way more so than bad and created a better lead sound.  I have wondered about that with old amps and there vintage quality . 

I went to Amplifiedparts.com to check prices.  At 4 to 5 dollars apiece, for .022, they seem expensive compared to other caps available on the site.  I'm not sure how to even test the qualities of the different samples.  I suppose a 2520 amp circuit with a cap under test position and then some music listening with an A/B switch.   

Now days I can't stand playing that amp up at volume.  Just to hard on the ears.  ???   

 

[sarakisof]

nice inputs guys

The axial mounted component is getting harder to find I normally end up using box caps with radial pins ,

so true